Electrical apparatus



Dec. 15,1925. v

J. n. HILLIARD ELCTRICAL APPARATUS `Filed June 5, 1922 His Attorney ITM/enter John D.Hi||iar-d. bs

Patented Dec. 15, 1925.

UNITED STATES PATENT OFFICE.

JOHN D. HILLIARI)J OF SCI-IENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL APPARATUS.

Application filed .Tune 5,

To @ZZ whom z'z may concern:

Be it known that I, JOHN D. HILLIARD, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Electrical Apparatus, of which the following is a specification.

My invention relates to electrical apparatus in which parts thereof are surrounded by an insulating fluid, and particularly to electric switches having contacts separable in an insulating fluid.

In case there is a considerable current flowing through the switch when its contacts are separated, a high pressure is developed within the fluid containing vessel by reason of the vaporization and dissociation of the fluid in which the contacts are immersed. The sudden formation of gas produces a severe hammer blow or impulse propagated al: high speed through the fluid mass acting to stress the tank, and in addition, slower stresses produced by the expansion of the gas and in certain cases by secondary eXplosions which may be caused by the ignition of gas on contact Vwith the air above the surface of the fluid. The stresses produced are usually manifested by the blowing of the fluid out of the tank and by the distortion or a possible bursting of the tank.

One object of my invention is to provide a removable means or means which may be readily attached to existing switches whereby the gases generated as the switch opens, may expand without greatly increasing the pressure within the fluid tank and without greatly accelerating the fluid mass to produce sudden or impulse stresses.

For this purpose I provide the fluid tank with one or more expansion chambers and a means for removably securing the same in place within the tank. The expansion chambers are formed of gas-tight casings closed at the top and open at or near the bottom.

The openings are located beneath the surface of the fluid in the tank and the chambers above the opening contain a gas which is adapted to be compressed when fluid under the influence of pressure created at the open .Of the .Switch enters :the chamber. 'The 1922. sensi/N0. 565,937.

compression ofthe gas in the expansion chambers produces a cushioning effect to relieve the pressure otherwise exerted upon the walls of the tar-.k and also prevents the throwing of fluid from the tank. The eX- pansion chambers may be of any desired shape and are adapted for insertion in tanks of switches previously manufactured.

Other objects and advantages will appear from the following description taken in connection with the accompanying drawing, wherein Fig. 1 is a sectional view of one form of switch embodying my invention, each of the parts being shown in elevation; Fig. 2 is a horizontal section taken on the line 2-2 of Fig. '1, the contact being shown in elevation; Fig. 3 is a horizontal sectional view of a rectangular tank similar to Fig. 2,

adapted to contain four expansion chambers,

the contacts in this case also being shown in elevation; Fig. 4f is a side elevation; and Fig. 5 a bottom plan view of a form of casing which is adapted for insertion in a cyline drical tank; Fig. 6 is a side elevation; and Fig. 7 a bottom plan view of a cylindrical casing adapted for insertion in any form of tank; Fig. 8 is a bottom plan view of a segmental casing adapted to occupy a segment of a cylindrical tank; Fig. 9 is a horizontal sectional view partly in elevation of a cylindrical tank of a single pole switch adapted to contain two segmental expansion chambers such as shown in Fig. 7, and Fig. 10

is a similar view of a cylindrical tank for` a triple pole switch.

By referring to Figs. 1 and 2, in which are shown a switch frame 11 through which passes an insulating bushing 12 carrying a stationary electrode 13, the insulating bushing 12 being held in place bythe clamp 14. A movable electrode 15 is supported on a bridging member 16, and is operated by a contact rod 17. The switch frame 11 supports a fluid tank which is lined with insulating material 21 and adapted to contain an insulating liquid 22, the normal height of which is indicated by the shading. A removable compression chamber casing 25 is adapted to be inserted behind an angle iron support 26 and is secured to the fluid tank Qc'vat the .top ,by the ,bolts 27. lf desired,

other terms of releasable securing means other than the bolts 27 may be used. I have shown the casing 25 as composed of insulating material, but it is clear that the same may be constructed ol metal and covered with insulating material.

By referring to Fig. 3 will be seen a rectangular switch tank adapted to receive four expansion chambers similar to the ones described above arranged to surround the electrodes.

In Figs. l and 5 will be seen views of an annular expansion chamber casing adapted. for insertion in a cylindrical tank. This casing is made up of two cylindrical walls and a top member, the inner wall being shorter than the outer. This casing may be made of insulating material or of metal, but if of metal the top and side nearer the electrode should be covered with insulating material.

In Figs. 6 andy 7 will be seen views oit a cylindrical expansion chamber casing adapted for insertion in any convenient place in the tank of a fluid break switch such as in the corners ot rectangular tanks. This casing is formed by sealing` one end of a tube to form the top member and cutting away part of the lower portions of the tube to provide an entrance opening for the liquid. f

In Fig. 8 will be seen a bottom view of an expansion chamber segmental in form adapted to be inserted in a cylindrical tank, an elevation of which would be similar to Fig. 6. This casing is termed by joining a'segment of a cylindrical tube with a flat member to form the sides and by sealing the top as explained in the description of the previous casings. Therflat member is shorter than the segmental member and part of the latter is cut away at the bottom to provide an entrance opening for the liquid. This casing may be made of insulating material or of metal, but if of metal the top and flat side'should be covered with insulating material.

In Fig. 9 is shown a cylindrical tank and the electrodes of a single pole switch having two of the segmental expansion chamber casings shown in Fig. 8 placed on either side of the electrodes.

In Fig. 10 is shown a cylindrical tank and the electrodes of a triple pole switch having two 'of these casings placed on either end of the electrodes.

The sequence of operation from the closed position of the switch under load follows: Manual or automatic operation of the tripping device (not shown, but which may, for example, be similar to that disclosed in Letters Patent No. 942,491, granted to lVilliam L. R. Emmet and Edward M. Hewlett, December 7, 1909) causes downward movement of the movable electrode l5 Fig, 1)

and its separation from the stationary electrodes 13. An arc is started, the intensity of which is sufficient to vaporize a portion of the liquid, The amount of gas generated depends among other things upon the current flowing in the arc and upon the length of time that the are is maintained. As the gas is generated, a high pressure suddenly develops within the tank which is relieved by part ot the liquid being forced into the expansion chambers, compressing the air or inert gas entrapped therein. This pressure is generated rapidly within the tank and except for secondary explosions which may occur in the air above the liquidv level continues to be developed until the arc is ruptured. Normal atmospheric pressure within the tank is restored by leakage, during which the compression upon the entrapped air or inert gas within the eXpansion chamber will be relieved. and the switch will be in a position to function again.

While I have shown my invention applied to an electric switch, it is clear that the same may be' applied to other electrical apparatus which have parts wholly or partially immersed in a fluid in which gases may be formed from a static discharge or from other causes.

This is a continuation in part of my application for Letters Patent, Serial No. 332,621, filed October 23, 1919, Patent No. 1,537,352, May 12, 1925.

That I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a switch, a. tank adapted to contain a liquid, contacts separable beneath the surface of said liquid to form an arc, a casing forming a chamber closed at the top and open at a point below the surface of said liquid, said casing being formed with a wall arranged to rest on the bottom of said tank andV to extend upwardly along a wall of the tank, and means for removably holding said casing in place comprising a lug secured to the tank and adapted to engage the said wall at its lowerV portion. i

2. In a switch of the fluid break type having a tank and cover therefor, a remo-vable expansion chamber comprising a top and side walls of a length sufficient to extend from the fluid level in the switch tank to a point substantially opposite the contacts, and means whereby said chamber may be secured in an inverted position in the switch tank with one of its side walls against a side wall of said tank.

In a switch comprising` atank containing ninsulating fluid and relatively movable contacts immersed therein, a plurality of separate removable expansion chambers each comprising a top and side walls and arranged in said fluid respectively on opposite sides of said contacts with their open sides .in proximity thereto and means for securing said chambers in inverted position in seid tanks whereby the rupturing capacity of said switch is increased.

4f. An attachment for an electric switch of the fluid break type for increasing the circuit interrupting capacity of the switch comprising an open Vessel adapted to be immersed in an inverted position in the fluid of the switch, and means for securing it to the side of the switch tank.

In Witness whereof, I have hereunto set my hand this iirst day of June, 1922.

JOHN D. HILLIARD. 

